The invention concerns a connector for an optical fibre according to the preamble of claim 1. With optical plug-in connectors, a Fresnel reflection occurs on the fibre end surfaces of the optical fibres to be connected to one another, whereby a return of light into the transmitting fibre can be the result. This light, which is reflected back into the transmitter, adversely effects the quality of the transmission system and is therefore most undesireable. For this reason the fibre end surface is inclined, in order to achieve a return loss which is as high as possible. The reflected light beams are in this way only transmitted back to a slight extent, whilst the higher proportion are radiated away to the outside of the optical fibre. The theoretical basis for calculation of the largest possible return loss is known to the expert.
With a few known connectors, the face is inclined flat through grinding in such a way that the fibre end surface, even with the largest possible eccentricity of the optical fibre, will be completely included within the area of the inclination. This form of inclination has, however, the disadvantage that only a section is left over as a face, which is arranged at rightangles to the middle axis of the connector pin. In principle, the connector pin has the form of a cylinder which has been cut off obliquely. Since the face of the connector simultaneously forms the contact surface for both of the opposing connector pins, this type of configuration is very disadvantageous. With the extremely small diameter of the connector pins, for example 2.5 mm, a very small contact surface remains between both the coupled connector pins. Just a slight slanting of the remaining contact surfaces can strongly influence the transmission loss.
A method of grinding connector end surfaces has been made known through JP-A-57/156159, with which, in order to form an inclination, a tool with a spherical grinding surface is led against the face, whereby the rotating axis of the tool runs eccentrically to the axis of the fibre. In this way the contact surface on the connector face can indeed be somewhat enlarged, since, for example, it runs slightly crescent shaped. A clean boundary between the inclination and the remaining contact surface is at the same time no longer ensured. Depending on the material and the quality of the tool, the smallest faults or burrs can occur which adversely effect the flatness of the contact surface and with that the quality of the plug-in connection. The grinding procedure becomes problematic especially if the connector pin also exhibits two different materials on the face, for example an outer ferrule of hard metal and a core of a flexible alloy.